Cooperative bimetallic catalysis in asymmetric allylic substitution

Strategies using a chiral metal catalyst and the cooperative effect of a second achiral or chiral metal catalyst for asymmetric allylic substitution reactions are discussed.

Direct use of allylic alcohols and allylic amines in palladium-catalyzed allylic amination

Allylic alcohols and allylic amines were directly utilized in a Pd-catalyzed hydrogen-bond-activated allylic amination under mild reaction conditions in the absence of any additives. The catalytic system is compatible with a variety of functional groups and can be used to prepare a wide range of linear allylic amines in good to excellent yields.

Ir/BiphPHOX-catalyzed asymmetric hydrogenation of 3-substituted 2,5-dihydropyrroles and 2,5-dihydrothiophene 1,1-dioxides

An efficient asymmetric hydrogenation of 3-substituted 2,5-dihydropyrroles and 2,5-dihydrothiophene 1,1-dioxides was developed using an Ir catalyst with an axially flexible chiral phosphine-oxazoline ligand.

The synthesis of planar chiral pseudo-gem aminophosphine pre-ligands based on [2.2]paracyclophane

We have synthesized three pseudo-gem [2.2]paracyclophane-derived P,N-ligands and report preliminary activity studies for the amination of aryl bromides and chlorides.

NeoPHOX - a structurally tunable ligand system for asymmetric catalysis

A synthesis of new NeoPHOX ligands derived from serine or threonine has been developed. The central intermediate is a NeoPHOX derivative bearing a methoxycarbonyl group at the stereogenic center next to the oxazoline N atom. The addition of methylmagnesium chloride leads to a tertiary alcohol, which can be acylated or silylated to produce NeoPHOX ligands with different sterical demand. The new NeoPHOX ligands were tested in the iridium-catalyzed asymmetric hydrogenation and palladium-catalyzed allylic substitution. In both reactions high enantioselectivities were achieved, that were comparable to the enantioselectivities obtained with the up to now best NeoPHOX ligand derived from expensive tert-leucine.

Carbohydrates as enantioinduction components in stereoselective catalysis

Carbohydrate derivatives are readily available chiral molecules, yet they are infrequently employed as enantioinduction components in stereoselective catalysis. In this review, synthetic approaches to carbohydrate-based ligands and catalysts are outlined, along with example applications in enantioselective catalysis. A wide range of carbohydrate-based functionality is covered, and key trends and future opportunities are identified.

Synthesis and catalytic applications of ruthenium(ii)–phosphino-oxime complexes

Ruthenium complexes containing a phosphino-oxime ligand have been synthesized, and their catalytic utility for the rearrangement of aldoximes, as well as for the α-alkylation/reduction of acetophenones with primary alcohols, demonstrated.

Synthesis of P-stereogenic diarylphosphinic amides by directed lithiation: transformation into tertiary phosphine oxides via methanolysis, aryne chemistry and complexation behaviour toward zinc(ii)

A general synthesis of P-stereogenic compoundsviaDoLi–electrophilic quenching of phosphinic amides and subsequent derivatizations is reported.

Fei-Phos ligand-controlled asymmetric palladium-catalyzed allylic substitutions with structurally diverse nucleophiles: scope and limitations

The asymmetric palladium-catalysed alkylation of structurally diverse nucleophiles, including alcohols, activated methylene compounds, indoles, and aromatic amines, led to the formation of corresponding products in good yields and high enantioselectivities (up to 99% ee).

A mechanistic study on multifunctional Fei-Phos ligand-controlled asymmetric palladium-catalyzed allylic substitutions

Mechanistic studies were performed for the clarification of the role of multifunctional Fei-Phos in allylic substitution reactions, in which it is proved to be a diphosphine-controlled catalytic asymmetric allylic alkylation.

A triazine-phosphite polymeric ligand bearing cage-like P,N-ligation sites: an efficient ligand in the nickel-catalyzed amination of aryl chlorides and phenols

A reusable polymeric material containing P,N-ligation sites was prepared by a facile one-step route for application in transition-metal catalysis as a reusable P,N-ligand.

Palladacycle promoted base controlled regio- and enantioselective hydrophosphination of 2-pyridylacrylate/amide and the cytotoxicity of their gold complexes

The regioselective asymmetric hydrophosphination of pyridine-functionalized alkenes can be achieved in the presence of stoichiometric amounts of the chiral palladium complex (R)-1. The presence or absence of base affords the respective β- and α-adducts with excellent regiocontrol. Chiral gold-phosphine complexes incorporating the adducts exhibited good in vitro anticancer activity against the breast cancer cell line MDA-MB-231. Selectivity between the cancer cell line and normal cells was also observed.

Synthesis and Exploration of Electronically Modified (R)-5,5-Dimethyl-(p-CF3)3-i-PrPHOX in Palladium-Catalyzed Enantio- and Diastereoselective Allylic Alkylation: A Practical Alternative to (R)-(p-CF3)3-t-BuPHOX

The synthesis of the novel electronically modified phosphinooxazoline (PHOX) ligand, (R)-5,5-dimethyl-(p-CF₃)₃-i-PrPHOX, is described. The utility of this PHOX ligand is explored in both enantio- and diastereoselective palladium-catalyzed allylic alkylations. These investigations prove (R)-5,5-dimethyl-(p-CF₃)₃-i-PrPHOX to be an effective and cost-efficient alternative to electronically modified PHOX ligands derived from the prohibitively expensive (R)-t-leucine.

Dehydrogenative borylation: the dark horse in metal-catalyzed hydroborations and diborations?

Metal-catalyzed hydroborations and diborations frequently give “unwanted” side products arising from a competing dehydrogenative borylation reaction. While catalyst development initially focused on avoiding this “deleterious” pathway, fine tuning of a catalyst system could provide an efficient method to generate unsaturated alkenylboronate esters, synthetically valuable synthons for the Suzuki-Miyaura cross-coupling reaction. The aim of this review is to highlight the history and development of the dehydrogenative borylation reaction in the metal-catalyzed synthesis of alkenylboronate esters.

A novel polymer containing phosphorus–nitrogen ligands for stabilization of palladium nanoparticles: an efficient and recyclable catalyst for Suzuki and Sonogashira reactions in neat water

Highly monodispersed palladium nanoparticles supported on polymer containing phosphorus and nitrogen ligands was successfully synthesized, characterized and used in Suzuki and Sonogashira coupling reactions in water.

Palladium(ii) complexes with a phosphino-oxime ligand: synthesis, structure and applications to the catalytic rearrangement and dehydration of aldoximes

The catalytic rearrangement and dehydration of aldoximes with phosphino-oxime-palladium complexes is described.

Stereoselective coordination: a six-membered P,N-chelate tailored for asymmetric allylic alkylation

Six-membered chelate complexes [Pd(1a–b)Cl₂], (2a–b) and [Pd(1a–b)(η³-PhCHCHCHPh)]BF₄, (3a–b) of P,N-type ligands 1a, ((2S,4S)-2-diphenyl-phosphino-4-isopropylamino-pentane) and 1b, ((2S,4S)-2-diphenyl-phosphino-4-methylamino-pentane) have been prepared.

Reaction of β-enaminones and acetylene dicarboxylates: synthesis of substituted 1,2-dihydropyridinones

Synthesis of dihydropyridinones was achieved by reaction of β-enaminones with acetylene dicarboxylates without using transition metal/catalyst.

Development of (trimethylsilyl)ethyl ester protected enolates and applications in palladium-catalyzed enantioselective allylic alkylation: intermolecular cross-coupling of functionalized electrophiles

The development of (trimethylsilyl)ethyl ester protected enolates is reported. The application of this class of compounds in palladium-catalyzed asymmetric allylic alkylation is explored, yielding a variety of α-quaternary six- and seven-membered ketones and lactams. Independent coupling partner synthesis engenders enhanced allyl substrate scope relative to traditional β-ketoester substrates; highly functionalized α-quaternary ketones generated by the union of (trimethylsilyl)ethyl β-ketoesters and sensitive allylic alkylation coupling partners serve to demonstrate the utility of this method for complex fragment coupling.